1. Field
Example embodiments relate to methods of driving a hybrid type inkjet printing apparatus using both a piezoelectric force and an electrostatic force.
2. Description of the Related Art
An inkjet printing apparatus may eject droplets of printing ink onto a desired position on a printing medium (e.g., printing paper) using an inkjet head, thereby printing an image of a particular color on the printing paper. The inkjet printing apparatus has been increasingly used in connection with flat display devices (e.g., liquid crystal displays (LCD), organic light emitting devices (OLED)), flexible display devices (e.g., electronic paper (E-paper)), printed electronics (e.g., metal wiring), and organic thin film transistors (OTFT). When the inkjet printing apparatus is used in relation to the above-described display devices or printed electronics, properties like resolution and precision printing are some of the significant technical issues facing manufacturing processes using the inkjet printing apparatus.
Inkjet printing apparatuses may use various ink ejection methods, e.g., piezoelectric ink ejection, electrostatic ink ejection. In a piezoelectric ink ejection method, ink is ejected by deforming a piezoelectric body, while in an electrostatic ink ejection method, ink is ejected by electrostatic force. The electrostatic ink ejection method may be classified as an electrostatic induction ejection method that uses electrostatic induction to eject ink and also as a method in which ink droplets are ejected after accumulating charged pigments by electrostatic force.
An inkjet printing apparatus using a piezoelectric method ejects ink using a drop on demand (DOD) method. Such an inkjet printing apparatus may provide relatively easy control of a printing operation and be driven in a relatively simple manner. Also, because such an inkjet printing apparatus generates ejection energy by mechanical deformation of a piezoelectric body, there is no particular limitation as to the type of ink used. However, it is relatively difficult to eject fine droplets having a size of several picoliters or smaller using a piezoelectric inkjet printing apparatus. Also, the linearity of the ejected ink droplets may be decreased.
An inkjet printing apparatus using an electrostatic method may realize fine droplets with relative ease. Such an apparatus may also be driven in a relatively simple manner with satisfactory linearity of the ejected ink droplets. Thus, such an inkjet printing apparatus may be effective for precision printing. However, when using an electrostatic inkjet printing apparatus that uses electrostatic induction, it may be relatively difficult to control each of the nozzles that form the ink droplets. It may also be relatively difficult to eject ink from multiple nozzles using a DOD method. Furthermore, an electrostatic inkjet printing apparatus using charged pigments needs to accumulate pigments of relatively high density, and the ejection speed thereof and the type of ink used therein may also be limited.